1. Technical Field
The present invention relates to an apparatus and a method for removing semiconductor chips and an apparatus for feeding semiconductor chips, in which one out of a plurality of semiconductor chips formed from a diced semiconductor wafer is removed from a pressure-sensitive adhesive sheet that holds the semiconductor chips by adhering thereto, and the semiconductor chip is ready to be extracted (picked-up) from the pressure-sensitive adhesive sheet.
2. Description of the Related Art
Conventionally, a plurality of semiconductor chips (hereinbelow referred to as IC chips) formed from a semiconductor wafer (hereinbelow referred to as a wafer) being diced are stored and transferred in the state of adhering to a wafer sheet (or a wafer tape) exemplifying the pressure-sensitive adhesive sheet. In order to enable one IC chip out of a plurality of IC chips in such a state of adhering to a wafer sheet to be ready to be taken out, the target IC chip is pushed up from the bottom surface of the wafer sheet, and the IC chip is removed from the wafer sheet.
However, IC chips are becoming smaller in a thickness and size, which causes a problem in that such thinner IC chips may suffer damage such as breakage of the IC chips during the push-up operation by the push-up pin.
In order to prevent the occurrence of such damage to the IC chips, for example, a method for performing the push-up operation while slowly raising the push-up pin has been considered, though such a method takes a long time and therefore is not practical.
Further, in an attempt to solve such a problem, there has conventionally been devised a method for preventing breakage of the IC chips by forming fine protruding and recess portions on a contact surface of a push-up apparatus, thereby reducing adhesion of the IC chips to the wafer sheet with the use of the protruding and recess portions. Then the IC chips are pushed up by a push-up pin so that the force necessary for the push-up operation is diminished (see, e.g., Japanese unexamined patent publication No. H11-274181, and Japanese unexamined patent publication No. 2000-195877). Such a method will be described below with reference to drawings FIGS. 8 and 9.
FIG. 8 is a schematic view showing an enlarged fragmental cross section of a contact portion of such a push-up apparatus with a wafer sheet. As shown in FIG. 8, the IC chips 112 adhere to the top surface of the wafer sheet 111 with a bond 113. Such respective IC chips 112 are, for example, removed from the wafer sheet 111, and taken out in the state of being sucked and held by a mounting head so as to be mounted on a circuit board. Moreover, as shown in FIG. 8, inside a cylinder-shaped pepper pot 121, which has a cylindrical casing like a pepper pot in the push-up apparatus, an elevating member 122 is housed in such a manner that allows up and down movement. Further, a push-up pin 123 for pushing up the IC chip 112 is provided on the top surface of the elevating member 122, and a cover plate 124 is provided on the top surface of the pepper pot 121. It is to be noted that reference numeral 119 denotes an outer cylinder serving as a stopper for attaching the cover plate 124 on the pepper pot 121 in a detachable manner.
Further, as shown in FIG. 8, a number of edged protruding and recess portions are formed on the top surface of the cover plate 124, and a number of hole portions 125 are formed in the respective recess portions. Among the recess portions, the hole portion 125 in the middle is a pin hole for allowing the push-up pin 123 to protrude from the inside of the pepper pot 121 (shown in phantom in FIG. 9), and the hole portions 125 around the middle hole portion are vacuum holes for vacuum-holding the wafer sheet 111.
The procedure for performing sucking and extracting operation through push-up of the IC chips 112 in the push-up apparatus having such a structure will now be described. First, as shown in FIG. 8, the pepper pot 121 is raised to press the cover plate 124 to the bottom surface of the wafer sheet 111. At the same time, the inside of the pepper pot 121 is vacuum-sucked by a vacuum suction means (not shown) so that the wafer sheet 111 is sucked and held onto the top surface of the cover plate 124 through the hole portions 125. Moreover, since the respective hole portions 125 are formed in the recess portions, the wafer sheet 111 is sucked to the surface of the recess portions, by which, as shown in FIG. 9, the wafer sheet 111 is forcedly removed from the bottom surface of the IC chip 112, and the IC chip 112 now only partially adhering to the top surface of the protruding portions. In this state, the push-up pin 123 is raised and protruded out of the hole portion 125 to push up the IC chip 112 while a suction nozzle 116 of a mounting head 115 vacuum-holds the IC chip 112 so that the IC chip 112 can be extracted.
In the sucking and extracting operation, the IC chip 112 is partially removed from the wafer sheet 111 by vacuum suction force of the hole portions 125, and in this partially removed state, the IC chip 112 is pushed up by the push-up pin 123. Consequently, the adhesion of the IC chip 112 by the bond 113 is weakened and so the force that is necessary to push up the IC chip 112 is decreased, which makes it possible to prevent the IC chip 112 from being damaged by the push-up operation.